The present invention relates to the area of transparent materials.
In many transparent materials, especially plastic-based transparent materials, for example polycarbonate etc., the difficulty arises of these materials sometimes having undesired refection properties which make it difficult or even impossible to use them for many applications.
Numerous attempts have thus been made to design transparent materials to be less reflective, especially by applying further coatings to them.
To this end it has been proposed that reflection be reduced by a so-called “flower-like alumina” coating (see Yamaguchi et al, Journal of Sol-Gel Science & Technology, 2005, 33, 117-120). However this approach demands a tempering step at increased temperatures (appr. 400° C.).
Other proposed coatings include multicoat systems with alternating refractive indices, e.g. multicoat systems comprising SiO2 and TiO2. However these also require tempering steps, mostly at temperatures of more than 400° C. (see M. Walther, OTTI Seminar Regensburg, September 2005). Other systems use coatings made of TiO2 and MgF2 (see EP 564 134 B1), in which additional fluorohydrocarbon resins are provided. The disadvantage of this system once again lies in it being hard to apply.
In many examples in accordance with the related art, especially for solidifying and hardening, temperatures of 400° C. and more are needed moreover in order to achieve the desired effects. However many substrates, especially plastics, but also metals are destroyed or attacked or lose specific properties under these conditions. Thus for example a few common plastics, such as PMMA or PC have a long-term usable temperature which does not exceed 100° C. and a few metals and alloys lose their hardness at increased temperature e.g. by transformations in the inner structure.
Furthermore methods such as CVD or PVD exist which require a vacuum and thus make a simple and continuous substrate production difficult.